Does Hydraulic Redistribution Increase Microbial Activity in the Rhizosphere?

EPA Grant Number: FP916339
Title: Does Hydraulic Redistribution Increase Microbial Activity in the Rhizosphere?
Investigators: Herron, Patrick M.
Institution: University of Connecticut
EPA Project Officer: Graham, Karen
Project Period: January 1, 2004 through December 31, 2004
Project Amount: $104,658
RFA: STAR Graduate Fellowships (2004) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Terrestrial Ecology and Ecosystems , Ecological Indicators/Assessment/Restoration


Hydraulic redistribution is the movement of water from wetter soils, through plant roots, into drier soils along a water potential gradient, usually at night when transpiration is negligible. This hydraulic redistribution of water into shallow, nutrient-rich soil layers may be important for maintaining soil microbial activity when soils dry, and thus potentially enhance nutrient availability to plants. Experiments testing these ideas are surprisingly few, and to date, they have been confined to isolated greenhouse measures. The objective of this study is to link mechanistic information about microbial response to water movement out of roots to potential resulting patterns in nutrient availability in space and time around plants.


This research combines integrated greenhouse and field studies that take advantage of the demonstrated ability of the common plant Artemisia tridentata (sagebrush) to redistribute water from wetter to drier soils in Western U.S. landscapes. Using genetically engineered microbiosensors in greenhouse experiments, and soil, plant, and microbial assays in the field in Utah, redistribution of water from moist to dry soil by plant roots will be examined for its ability to promote nutrient cycling around and nutrient availability to plant roots. Enhanced nutrient availability in turn potentially leads to enhanced photosynthesis, growth, and reproductive yield of plants actively redistributing water in dry landscapes; these plant characteristics will be examined. Our emphasis on mechanistic underpinnings of patterns of net mineralization or immobilization induced by hydraulic redistribution is particularly important now because ecosystem function in semi-arid and arid landscapes in the United States is being changed significantly by a number of human influences, including altered fire regimes and invasion by exotic grasses.

Supplemental Keywords:

fellowship, hydraulic redistribution, water redistribution, semi-arid, arid landscapes, soils, nutrient cycling,, RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Monitoring/Modeling, Environmental Monitoring, Ecology and Ecosystems, biosensing, environmental measurement, rhizosphere, hydrologic tracers, arid landscapes, nutrient monitoring , biosensors, hydrologic modeling, microbial populations

Progress and Final Reports:

  • Final